Unit 3 — Assembly and Setup

TM-GEAR-010 — Open Handout TM Chapter: Chapter 4 ELOs: Execute assembly steps in the correct sequence; verify build quality before operation Estimated time: 20 minutes

Step 1: Read the TM

Open TM-GEAR-010. Read Chapter 4 — Construction and Assembly completely.

Then come back here.

Chapter 4 Content

4-1 Ground Rod Installation

  1. Drive two 8′ ground rods at least 16′ apart (one rod length spacing minimum per NEC 250). Rods must be buried full depth (8′/2.4 m).
  2. Bond rods together with #6 AWG bare copper, buried 300 mm below grade. Use irreversible compression connectors (Burndy or equivalent) — never rely on wire wrapped around the rod.

  3. Run the ground conductor from the rod cluster to the entry panel via the shortest possible path (4-2 Entry Panel

  4. Mount the copper panel on the exterior wall at the point where all antenna cables enter the shack. Mount as close to the ground rod as possible.

  5. All coaxial feedlines must pass through the panel via GDT-equipped bulkhead connectors. All cable shields must bond directly to the panel at this point.
  6. Bond the panel to the ground rod cluster with a minimum 1/2″ copper strap (no wire — strap has lower RF impedance).

Assembly Quality

Chapter 4 specifies 6 construction/assembly steps.

The assembly directly determines RF performance. Common errors: - RF leads too long — lead inductance raises SWR and limits high-frequency performance - Cold solder joints on RF nodes — high resistance causes signal loss and intermittent behavior - Ground loops — multiple ground paths at different potentials cause noise and calibration errors - Ferrite winding errors — wrong turn count or direction reverses transformer polarity or changes impedance ratio - Incorrect winding direction on toroidal transformers — affects phase and common-mode rejection

If Chapter 4 specifies a verification step after assembly (e.g., "verify DC resistance = X before proceeding"), do it. Those checks exist because they are the most common failure points.

Self-Check Questions

SC3-1. How many assembly steps does Chapter 4 specify?

SC3-2. What is the first assembly step? State it exactly from the TM.

SC3-3. Does Chapter 4 specify maximum lead length anywhere? If so, what is the limit and why?

SC3-4. Does Chapter 4 require a bench verification after assembly? What does it check?

SC3-5. What would you do if a winding resistance measurement came out wrong during assembly verification?

Answer Key

SC3-1. Count the numbered steps in Chapter 4.

SC3-2. See Chapter 4, step 1. Copy it exactly.

SC3-3. RF lead length limits are typically 10–15 mm for HF circuits. Longer leads add ~1–2 nH per mm, raising inductive reactance at high frequencies.

SC3-4. Scan Chapter 4 for verification steps. Common checks: DC resistance, winding balance, null depth on test signal, impedance ratio.

SC3-5. Stop assembly. Diagnose before proceeding — a winding error found before completion is much easier to fix than one discovered after the unit is boxed.

Checkpoint

Before proceeding: - [ ] You have read Chapter 4 completely - [ ] You can state the number of assembly steps and the first and last steps - [ ] You understand how assembly quality affects RF performance

→ Proceed to Unit 4